Warning: Graphic content.
A teenager has described the anguish of hearing his brother and father fighting before seeing his dad up against a wall and bleeding heavily, having been stabbed six times.
The teen's older brother, who has interim name suppression, was later charged with murdering his father after the fight at a South Auckland property last year.
His trial began at the High Court in Auckland before a jury and Justice Ailsa Duffy this week.
Several suppression orders prevent media from revealing certain details about the killing.
Just hours after the incident, the younger brother, who said he was afraid of his father, told police what he saw and heard.
He recalled his battered mother having fled to his brother's home after his father had inflicted yet another beating on her.
But, the father followed her, and arrived at the house screaming and attempting to kick down the door.
"He kept banging on the window," the younger brother said in his interview, played before the court today.
He said his mum had a heavily swollen face around her eye. The family closed the curtains, locked the doors and turned off the lights to hide themselves from their abuser.
"[My dad] turned up and said stuff like, 'Is that bitch inside there?'
"My brother got mad 'cause he had seen my mum like that a thousand times."
As the heated exchange eased, the younger brother said, his sibling went outside to check that his father had left.
The accused walked out onto the deck, clutching a knife, when he says he was punched to the side of the head by his father who had been lurking in the shadows.
"It was very loud you could hear it," the younger sibling said of the punch, adding he was in the living room and looking after his baby brother at the time.
"I just heard the punch and someone scream and you could hear heavy footsteps on the ground ... Then the stabbing.
"I thought my dad had tried to kill him.
"My brother freaked out and stabbed him."
The younger brother also went outside and he saw his father "up against the wall with blood coming out of him".
"There was a lot of blood," he said.
He added his brother was apologising and crying: "I did ... I stabbed him."
The accused, who is in his 20s, accepts killing his father, in his 40s, but argues his actions were justified as he attempted to protect himself and his family.
Earlier in the trial the defendant's mother spoke of how she had been with her late husband for about two decades. They moved to Auckland with their children a few years ago, but she left the city after her husband was killed.
She told the court her husband would accuse her of "going out and sleeping around".
"[He'd] give me hidings for it," she said.
"Until I started bleeding and then he'd stop - I guess he thought it as seeing that he'd done his job."
Her children were also witnesses and victims of the abusive relationship from a young age, she said.
The younger brother said, under cross-examination, that his mum couldn't walk for days after one beating and that the children would often help nurse her injuries.
Crown prosecutor Gareth Kayes has told the court that the defendant stabbed his father six times, including the fatal strike to his chest, which penetrated the father's heart.
The son's defence team, led by Denise Wallwork, has said the father was "a monster" who "terrorised his family, both emotionally and physically".
The father, the defence claimed, was akin to the Once Were Warriors character Jake "the Muss" Heke.
During his police interview, the accused said his father had come "out of the dark" and punched him on the left side of the head, knocking him off the deck.
"Don't get me wrong here, [the father] had been nasty and hostile to the defendant and his family, particularly to [his wife]," Kayes said.
"[But] was [the son's] use of force proportionate and reasonable to the threat?"
The trial continues.